Load weight indicator for forklift trucks



Nov. 17, 1953 c. L. WETSEL LOAD WEIGHT INDICATOR FOR FORK-LIFT TRUCKSFiled April 7, 1952 CECIL .L. WETSEL M-M/ M ATTORNEYS Patented Nov. 17,1953 LOAD WEIGHT INDICATOR FOR FORK- LIFT TRUCKS Cecil L. Wetsel,Sacramento, Calif.

Application April 7, 1952, Serial No. 280,921

4 Claims.

In the use of a fork lift truck it is often desirable that the operatorknow the weight of each load picked up on the forks, and the presentinvention provides, as a major object, a novel indicator for suchpurposes.

Another important object of the present invention is to provide a loadweight indicator as above which is hydraulically operated; the deviceincluding a hydraulic gauge within view of the operator and calibratedin terms of weight, and a hydraulic pressure unit communicating with thegauge adapted to be subjected to the weight of the load in a novelmanner.

An additional object of this invention is to provide a load weightindicator as in the preceding paragraphs wherein the device isselectively operable, i. e. at the will of the operator of the fork lifttruck. This is accomplished by mounting the hydraulic pressure unit formovement, by power means, between a working position in the path of amember on the elevator frame of the fork lift truck, and a non-workingposition clear of said elevator frame.

A still further object of this invention is to provide a load weightindicator which is capable of being readily and conveniently applied, asan attachment, to a conventional fork lift truck; the device, when soattached, not in any way obstructing the operation of the truck.

It is also an object of the invention to provide a load weight indicatorwhich is designed for ease and economy of manufacture.

Still another object of the invention is to provide a practical,reliable and accurate load weight indicator for fork lift trucks, andone which will be exceedingly effective for the purpose for which it isdesigned.

These objects are accomplished by means of such structure and relativearrangement of parts as will fully appear by a persual of the followingspecification and claims.

In the drawings:

Fig. 1 is a side elevation of a fork lift truck embodying the presentinvention.

Fig. 2 is an enlarged rear elevation of the upper portion of the frameassembly of the truck showing particularly the mounting of the hydraulicpressure unit; the latter being shown in its nonworking position.

Fig. 3 is a similar view but shows the hydraulic pressure unit asshifted to its working position.

Fig. 4 is a top plan view of the structural arrangement as in Fig. 3.

Fig. 5 is an enlarged sectional elevation of the hydraulic pressure unitdetached.

Referring now more particularly to the characters of reference on thedrawings, the invention is here shown as mounted in connection with aconventional fork lift truck indicated generally at I, which truckincludes, at the front, an up standing main frame 2 having a movable orelevator frame 3 thereon. The elevator frame 3 is run up or down byconventional power means, and said elevator frame carries the forwardlyprojecting load supporting forks 4.

The present invention comprises a hydraulic gauge 5 calibrated in termsof weight and mounted on the fork lift truck I directly ahead of theoperators seat 6, whereby such gauge is disposed for easy reading.

The hydraulic gauge 5 is connected by a hydraulic pressure conduit 1,flexible at least in part, with a hydraulic pressure unit indicatedgenerally at 8.

The hydraulic pressure unit 3 comprises a relatively short upstandingcylinder 9 closed top and bottom. A piston l 0 works in the cylinder 9on a quantity of hydraulic fluid I I in said cylinder. A piston rod l2upstands from the piston l0 and-is slidable through a guide sleeve 13which projects upward from the top of the cylinder; such guide sleeve l3being enclosed within a protective housing M. The piston rod [2 projectssome distance above the guide sleeve l3 and protective housing 14 asshown.

The above described hydraulic pressure unit 8 is set on a horizontalplatform [5 which is fixed to and projects rearwardly from the centerportion of the top cross beam it of the main frame 2.

The hydraulic pressure unit 8 is formed at the bottom with a radial arm[1 which extends inwardly to a pivot l8 on the platform 15 substantiallycentrally of the latter. As so mounted, the hydraulic pressure unit 8 isswingable between a non-working position clear of the vertical path of9. lug I9 which projects rearwardly from the center of the top crossbeam 20 of the elevator frame 3, as shown in Fig. 2, and a workingposition directly below said lug l9 as shown in Fig. 3.

When the hydraulicpressure unit 8 is disposed in its working positiondirectly below the lug 19, the latter comes to rest on the piston rod [2shortly before the elevator frame 3 reaches its lowermost point ofmovement.

As a consequence, weight of the elevator frame 3 and the load 2| on theforks 4 are in their entirety imposed directly on the hydraulic pressureunit 8, i. e. on the piston I0 working against the fluid ll; it beingunderstood that the power means which works the elevator frame istotally relieved during the period of the weight recording. The cylinder9 is in communication with the conduit I so that pressure from thecylinder 9, produced by the load weight as above, is transmitted to andreflects itself in the gauge 5, which gauge has a tare corresponding tothe weight of the elevator frame 3 and forks 4 whence the gauge 5 readsdirectly and accurately in terms of the weight of lpad z l.

Afterthe'weight 'ofthe load 2| has been determined and recorded by theoperator, the hydraulic pressure unit 8 is swung out of the path of thelug l9 so that the elevator frame 3 may continue its downward movementuntil theforks 4 are at ground level; such movement of the unit I beingaccomplished by power means as'follows:

A small double acting power cylinder 22 extends laterally from the unit8, being connected between the latter and an outrigger arm 23 onthe-n'iain frame 2, the points of pivotal connection being imiioated at24 and 25. It-will be recognized that upon-actuation of the powercylinder 22 to extend it, the unit 8 is moved to working positionwhilecontraction of said power cylinder moves the unit l to non-workingposition.

The double acting power cylinder 22 is controlled by the operatorthrough the medium of a valve regulated fluid pressure supply conduitsystern-26 which includes a control valve 21 therein;

such valve being worked'by an -upstanding hand leverlfl.

With the described weight indicator, the weight of each'load' 2| pickedup by the fork lifttr-uck I is accurately-indicated to the truckoperator who notes the weight upon a suitable record. In this way thetotalweight of a load placed part by part on a hauling truck by the forklift-truck canine-accurately ascertained in order to preventoverloading. This is only one example'of many advantages whichaccrue-from use of the described load weight indicator.

present andpreferred construction of the device,

still in practice such deviations from such detail may beresorted to asdo-not form a departure from the spirit of the invention, as defined bythe appended claims.

Havingthus described the invention, the foland including an upwardlyprojecting-vertically movable element whose downward movement exertspressure on the fluid in the unit, a pressure gauge calibratedin termsof weight mounted on the truck, and a conduit between the gauge andunit; and a lug fixed on the elevator frame and *projectingtherefrom inoverhanging relation to the working position of said movable element andat a level to engage the same upon lowering of the'elevator frame toadjacent its lowest position on the main frame.

2. A'device asinclaim l, with means mounting the unit on the main framefor movement between a working position in vertical alinement with thelug to a position clear of the same.

3. A device as in claim l, in which the unit includes a vertical axiscylinder; a platform fixed on themain frame on which the cylinder rests,a radial arm projecting from the cylinder, and means pivoting the arm onthe platform in position to enable the cylinder tobe shiftedhorizontallybetween a working; position in vertical alinement with the lug to a'non-working position clear of said lug.

4. A device as in claimB, with means to shift the cylinder comprising abracket on-the main frame laterally offset from the cylinden and ahydraulic cylinder unit pivoted at one end on the bracket and at theother end on the cylinder in circumferentially offset relation to thearm.

CECIL L. WET'SEL.

References Cited in the file of this patent UNITED STATES PATENTS Number'Name Date -32,326 Winter .I\Iay 14, 1861 231,838 Moro Aug. 31, 18802,373,469 Grime Apr. 10, 1945 FOREIGN PATENTS Number Country 'Date 6,222Great Britain July '25, '1912 650,375 Great Britain Feb. 21, 1951

